Additive fabrication support structures

ABSTRACT

Some aspects provide a method of generating a support structure for an object, the support structure and the object to be fabricated via one or more additive fabrication techniques, comprising identifying one or more regions of the object as one or more regions to which mechanical support is to be provided, identifying one or more support points within at least a first region of the one or more regions, and generating the support structure for the object, the support structure comprising one or more support tips coupled to the object at the one or more support points, the support tips being generated based at least in part on a direction normal to the surface of the object at the respective support point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit as a continuation under 35 U.S.C.§120 of U.S. patent application Ser. No. 14/245,765, filed Apr. 4, 2014under Attorney Docket No. F0725.70000US01 and entitled “AdditiveFabrication Support Structures,” which claims the benefit of both U.S.Provisional Patent Application No. 61/808,714, filed Apr. 5, 2013,titled “Three-Dimensional Printing With Customizable SupportStructures,” and U.S. Provisional Patent Application No. 61/878,851,filed Sep. 17, 2013, titled “Support Structures for 3D Objects Formed inLayers,” each of which are hereby incorporated by reference in theirentirety.

FIELD OF INVENTION

The present invention relates generally to systems and methods forproviding and evaluating support structures, including supportstructures that are suitable for use in additive fabrication.

BACKGROUND

Additive fabrication, e.g., 3-dimensional (3D) printing, providestechniques for fabricating objects, typically by causing portions of abuilding material to solidify at specific locations. Additivefabrication techniques may include stereolithography, selective or fuseddeposition modeling, direct composite manufacturing, laminated objectmanufacturing, selective phase area deposition, multi-phase jetsolidification, ballistic particle manufacturing, particle deposition,laser sintering or combinations thereof. Many additive fabricationtechniques build parts by forming successive layers, which are typicallycross-sections of the desired object. Typically each layer is formedsuch that it adheres to either a previously formed layer or a substrateupon which the object is built.

When producing certain objects by additive fabrication, a supportstructure may be fabricated to provide mechanical support to the objectbeing fabricated. An object may contain regions that are not fullysupported by previously formed layers, and in such instances there maybe no suitable working surface during fabrication that can providesupport to those regions. By fabricating a support structure along withthe primary object, a working surface can be provided to non-fullysupported regions of the object during fabrication. Following thecompletion of the 3D printing process, the support structure is removedfrom the object through various post-processing steps.

In many cases, however, support structures can lead to surfacedeformations or other flaws in the object being fabricated, such asflaws caused by the attachment to the object and/or by the removal ofthe support structures from the object. The removal process inparticular can damage the object in numerous ways, including by leavingpart of the support structure behind, removing part of the object withthe support structure, damaging the object, or otherwise marring thesurface finish of the object. These flaws can be particularly apparentwhen support structures are fabricated using the same material as thedesired object.

SUMMARY

Systems and methods for providing and evaluating support structures,including those suitable for use in additive fabrication, are provided.

Some embodiments include a method of generating a support structure foran object, the support structure and the object to be fabricated via oneor more additive fabrication techniques, comprising identifying one ormore regions of the object as one or more regions to which mechanicalsupport is to be provided, identifying one or more support points withinat least a first region of the one or more regions, and generating thesupport structure for the object, the support structure comprising oneor more support tips coupled to the object at the one or more supportpoints, the support tips being generated based at least in part on adirection normal to the surface of the object at the respective supportpoint.

Some embodiments provide at least one non-transitory computer readablemedium comprising an executable program that, when executed, causes acomputer to perform a method of generating a support structure for anobject, the support structure and the object to be fabricated via one ormore additive fabrication techniques, the method comprising identifyingone or more regions of the object as one or more regions to whichmechanical support is to be provided, identifying one or more supportpoints within at least a first region of the one or more regions, andgenerating the support structure for the object, the support structurecomprising one or more support tips coupled to the object at the one ormore support points, the support tips being generated based at least inpart on a direction normal to the surface of the object at therespective support point.

Some embodiments provide an object, comprising an object body having oneor more regions to which mechanical support is provided, and ascaffolding providing said mechanical support to at least a first regionof the one or more regions, the scaffolding comprising one or moresupport tips coupled to the object body at a respective support point,the one or more support tips being coupled to the object body at anangle normal to the surface of the object at the respective supportpoint, wherein the object body and the scaffolding are fabricated viaone or more additive fabrication techniques.

Some embodiments include a method of generating a support structure foran object, the support structure and the object to be fabricated via oneor more additive fabrication techniques, comprising identifying two ormore support points on the surface of the object, and generating thesupport structure for the object, the support structure comprising twoor more linear support tips with substantially identical cross-sectionalareas, wherein the support tips are each coupled to the object at one ofthe support points in a direction so as to substantially minimizecontact between the respective support tip and the object.

Some embodiments include a method for evaluating a support structureassociated with a three-dimensional object, the support structure andobject to be fabricated via one or more additive fabrication techniques,comprising obtaining a representation of the support structure, whereinthe support structure is configured to provide mechanical support to atleast a first region of the object, calculating a supportedness valuefor the first region of the object, the supportedness value beingindicative of a degree of support that the support structure provides tothe first region, depicting the support structure and/or the object viaa graphical user interface, and indicating the supportedness value forthe first region of the object by coloring a portion of the graphicaluser interface using one or more colors, at least one of the one or morecolors being based at least in part on the supportedness value.

Some embodiments provide an apparatus for evaluating a support structureassociated with a three-dimensional object, the support structure andobject to be fabricated via one or more additive fabrication techniques,comprising at least one processor configured to obtain a representationof the support structure, wherein the support structure is configured toprovide mechanical support to at least a first region of the object,calculate a supportedness value for the first region of the object, thesupportedness value being indicative of a degree of support that thesupport structure provides to the first region, depict the supportstructure and/or the object via a graphical user interface presentedusing a display, and indicate the supportedness value for the firstregion of the object by coloring a portion of the graphical userinterface using one or more colors, at least one of the one or morecolors being based at least in part on the supportedness value.

Some embodiments provide at least one non-transitory computer readablemedium comprising an executable program that, when executed, causes acomputer to perform a method for evaluating a support structureassociated with a three-dimensional object, the support structure andobject to be fabricated via one or more additive fabrication techniques,the method comprising obtaining a representation of the supportstructure associated with a three-dimensional object, wherein thesupport structure is configured to provide mechanical support to atleast a first region of the object, calculating a supportedness valuefor the first region of the object, the supportedness value beingindicative of a degree of support that the support structure provides tothe first region, depicting the support structure and/or the object viaa graphical user interface, and indicating the supportedness value forthe first region of the object by coloring a portion of the graphicaluser interface using one or more colors, at least one of the one or morecolors being based at least in part on the supportedness value.

The foregoing is a non-limiting summary of the invention, which isdefined only by the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various FIGs. is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 depicts an object and a support structure that includes supporttips, according to some embodiments;

FIG. 2 depicts an object and a support structure that includes supporttips internal to the object, according to some embodiments;

FIG. 3 depicts an object and a support structure that includes supporttips whose geometry is varied based on self-supportedness of the object,according to some embodiments;

FIG. 4 depicts an object and a support structure that includes supporttips whose geometry is varied based on distance from an axis applyingforces during a fabrication process, according to some embodiments;

FIGS. 5A-B illustrates flow charts of exemplary processes for generatinga support structure for an object, according to some embodiments;

FIG. 6A illustrates an isometric 3-D representation of a supportstructure for a spherical object, according to some embodiments;

FIG. 6B illustrates an top-down 3-D representation of the supportstructure shown in FIG. 6A, according to some embodiments;

FIG. 7A illustrates a top-down schematic view of a first arrangement ofsupport tips arranged radially with long axis directed out from thecentroid of an object, according to some embodiments;

FIG. 7B illustrates a top-down schematic view of a second arrangement ofsupport tips arranged radially with long axis directed out from thecentroid of an object, according to some embodiments;

FIG. 7C illustrates a top-down schematic view of support tips arrangedlinearly with a long axis directed orthogonally from an expecteddirection of a force exerted during a fabrication process, according tosome embodiments;

FIG. 8 illustrates an exemplary object and an exemplary supportstructure, according to some embodiments;

FIG. 9A illustrates a first view of the exemplary object and exemplarysupport structure shown in FIG. 8 including an indication of thesupportedness of the object, according to some embodiments;

FIG. 9B illustrates a second view of the exemplary object and exemplarysupport structure shown in FIG. 8 including an indication of thesupportedness of the object, according to some embodiments;

FIG. 9C illustrates a third view of the exemplary object and exemplarysupport structure shown in FIG. 8 including an indication of thesupportedness of the object, according to some embodiments;

FIGS. 10A-B illustrates flow charts of processes for evaluating asupport structure associated with an object, according to someembodiments; and

FIG. 11 illustrates an example of a computing system environment onwhich aspects of the invention may be implemented.

DETAILED DESCRIPTION

Systems and methods for providing and evaluating support structures,including those suitable for use in additive fabrication, are provided.While support structures can aid in successful fabrication of certainobjects, support structures may lead to defects on those objects and maycause a user to spend significant effort in removing the structures. Byforming a support structure that minimizes contact with an object beingfabricated while still providing sufficient mechanical support to theobject, defects can be reduced and removal of the support structure canbe made easier without compromising the quality of the fabricatedobject. In particular, the inventors have recognized and appreciatedthat the use of support structure attachment points as described herein(also referred to as “support tips” or “tips”) may result in superiorperformance, easier post-processing, and cleaner removal thanconventional support techniques. Support tips may be fabricated usingthe same and/or different materials than are used to fabricate theunderlying support structure.

In some embodiments, a support structure may be generated that includesone or more support tips that couple the support structure to an object.Support tips may be oriented so as to limit the area of the surface ofthe object that makes contact with the support tips, thereby reducingthe number and/or size of defects that remain on the object after thesupport structure has been removed. For example, the support tips may beoriented normal to a point on the surface of the object where thesupport structure and object are coupled to one another. The normalorientation may, for at least some support tip geometries, ensure that aminimal area connects the support structure to the object.

In some embodiments, a support structure may include one or more supporttips oriented in directions based upon expected forces at the locationsat which the support tips are coupled to an object. For example, in someuse cases it may be beneficial to balance a desire for easy removal ofthe support structure (which, as described above, may include the use ofnormally-oriented support tips) with forces expected to be exertedduring the fabrication process. Accordingly, in some embodiments,support tips may be provided with an orientation based on adetermination of the mechanical support sufficient to support a regionof an object (e.g., lesser support may result in damage to the objectduring fabrication). The resulting support tip orientation may provideboth an improved removal process compared with conventional supportstructures while also ensuring that sufficient mechanical support isprovided during the fabrication process. In some embodiments, theorientation of a support tip is determined by applying an offset basedon a determination of the mechanical support sufficient to support aregion of an object to a direction normal to the surface of the objectat the location where the support tip couples to the object.

In some embodiments, support tips may be provided in a support structurewherein one or more of the support tips are mechanically weaker than thebulk of the support structure. For example, support tips may be thinnerthan aspects of the support structure. This may further aid a user inremoving the support structure from an object with less damage to theobject, and may additionally maximize clearance between the support andthe object, thereby allowing the user to remove the support structurewith greater ease.

In some embodiments, the mechanical strength of one or more support tipsin a support structure is based on the self-supportedness of a region ofan object to which the support structure is coupled. For example, a flatdownward facing region of an object may demand extensive support toavoid distortion and reduce cosmetic defects, and thus may demonstrate alow amount of self-supportedness; whereas a flat and almost verticalregion may be largely supported by regions beneath it and thus maydemonstrate a high amount of self-supportedness. In some use cases,therefore, it may be beneficial to provide mechanically stronger supporttips to regions having comparative low self-supportedness compared withregions having comparatively high self-supportedness.

In some use cases, differing portions of an object may, at differenttimes during the fabrication process, experience forces of differentmagnitudes and directions. Accordingly, in some embodiments, supporttips may have a mechanical strength that is based, at least in part, onforces expected to be experienced by portions of the object duringfabrication. For example, the stereolithography process used by machinessuch as the Form 1 from Formlabs, utilizes a “peel” step which separatescured resin from the bottom of a transparent tray of resin by pivotingthe tray at an axis at one end. The Form 1 system is described morefully in one or more of U.S. patent application Ser. No. 13/848,979,filed Mar. 22, 2013 and titled “3D Printer with Self-Leveling Platform”;and U.S. Patent Application Ser. No. 61/808,714, filed Apr. 5, 2013 andtitled “Three-Dimensional Printing with Customizable SupportStructures,” the disclosures of which are incorporated by referenceherein in their entireties. A “peel” step, as described above, can exerta greater force on parts of the object and part of the support structurethat are further from the axis. Accordingly, it may be beneficial inthis use case to increase the mechanical strength of support tips basedon their distance from the pivot axis, for example to increase thestrength in proportion to the distance from the axis.

While the advantages of support tips as described herein may provide forsuperior performance, easier post-processing, and cleaner removal thanconventional support techniques, trial and error on the part of a usermay still be required in order to produce a support structure havingadequate mechanical support. In many use cases, there is a varyingdegree of support that can be provided to an object, for example, interms of the volume of the support structure and in the number of pointsof contact between the support and the object being fabricated. Asupport structure including support tips as described herein may notinherently guarantee that sufficient mechanical support has beenprovided by the support structure, and a user may not be able toascertain whether such support has been provided without spending timefabricating the object and assessing its quality.

Accordingly, the inventors have further recognized and appreciated thatproviding an indication of supportedness of one or more regions of anobject based on a support structure can provide immediate feedback to auser, and may thereby allow a user to generate sufficient support for anobject without spending time fabricating the object. By additionallyincluding support tips in the support structure, a user may ensure thatan object will be supported in the desired way while also minimizing thesupport structure's effect on the quality of the fabricated object.

In some embodiments, the supportedness of one or more regions of anobject is presented to a user via a graphical user interface (GUI). Forexample, a visual indication of supportedness provided via a userinterface, which may include but is not limited to text, pictures,object shading, patterns, popups, colors, and/or combinations thereofmay be used to provide information to a user about the supportedness ofone or more regions of an object to be fabricated (which may include thewhole object).

In some embodiments, the supportedness of one or more regions of anobject is indicated by coloring one or more elements of the userinterface such that the color is indicative of supportedness. Forexample, areas of an object depicted in a GUI and/or areas of a supportstructure depicted in a GUI may be depicted using one or more colorsthat indicate a level of supportedness. In some use cases, it may bebeneficial to provide an indication of whether the supportedness of oneor more regions of an object is above or below a particularsupportedness threshold. For example, regions of an object havingsupportedness above a threshold may be colored using a first color(e.g., green), and regions of the object having supportedness below thethreshold may be colored using a second color (e.g., red).

In some embodiments, supportedness of an object is determined bysplitting the object into volume elements, or “voxels.” This may providefor certain mathematical techniques, such as finite element analysis, tobe applied. For example, the supportedness of each voxel may bedetermined using finite element analysis and thereby by considering thesupportedness of neighboring voxels.

Following below are more detailed descriptions of various conceptsrelated to, and embodiments of, 3D printed support structures. It shouldbe appreciated that various aspects described herein may be implementedin any of numerous ways. Examples of specific implementations areprovided herein for illustrative purposes only. In addition, the variousaspects described in the embodiments below may be used alone or in anycombination, and are not limited to the combinations explicitlydescribed herein.

Although the embodiments herein are primarily disclosed with respect tothe Form 1 3D Printer sold by Formlabs, Inc., the Assignee of thepresent application, and with respect to stereolithography, those havingordinary skill in the art will appreciate that the invention is equallyapplicable to other systems, including any additive fabricationtechnology that forms objects using layer-based deposition, such as, butnot limited to, thermoplastic extrusion. In some embodiments, objectand/or support structures fabricated via one or more additivefabrication techniques as described herein may be formed from, or maycomprise, a plurality of layers. For example, layer-based additivefabrication techniques may fabricate an object by formed a series oflayers, which may be detectable through observation of the object, andsuch layers may be any size, including any thickness between 10 micronsand 500 microns. In some use cases, a layer-based additive fabricationtechnique may fabricate an object that includes layers of differentthickness.

Although particular support generation methods have been described andshown herein, it is envisioned that the functionality of the variousmethods, systems, apparatus, objects, and computer readable mediadisclosed herein may be applied to any now known or hereafter devisedadditive fabrication technique wherein it is desired to add supports toan object being produced.

FIG. 1 depicts an object and a support structure that includes supporttips, according to some embodiments. System 100 includes build platform10 on which object 14 has been fabricated. The object is supported by asupport structure which includes scaffolding 12 and interfaces 18. Notethat, in the example of FIG. 1 (and in those of FIGS. 2-4), the buildplatform 10 is situated above the object being fabricated such that theobject 14 hangs down from the build platform during the fabricationprocess. While not all additive fabrication techniques may utilize thisconfiguration, the techniques described below nonetheless also apply toany other type of configuration, including deposition modelingtechniques and/or stereolithography techniques in which the buildplatform is located beneath the object being fabricated.

Scaffolding 12 is coupled to interfaces 18 between object 14 and thesupport structure. Interfaces 18 are also referred to herein as “supporttips” or “tips,” which as described above may provide improvedperformance, reliability, and may reduce the need for post-processing.In particular, the inclusion of support tips 18 in the support structuremay allow for support tips to be optimized in ways not suited to thesupport structure, particularly with respect to the ease with whichobject 14 can be released from the support tip attachment points.

In the example of FIG. 1, support tips 18 are generated that extend fromscaffolding 12 and intersect with object 14 at an angle normal to theinterfacing surface 16 of the object. Such support tips are preferably,but not necessarily, mechanically weaker than the scaffolding. Byorienting support tips to the normals of an object surface, a user mayremove the support structure (being the combination of the support tipsand the scaffolding) from an object with greater ease and with lessdamage to the object. In addition, the use of a normal incident anglemay assist a user in applying shear forces to a support tip whileseparating the support tip from the object, while reducing thelikelihood of damage to the object. In these ways, time consumingpost-processing can be reduced and object quality improved.

Conventional support structures typically intersect with an object insuch a way as to increase the surface area in contact beyond the minimumcross section of the support structure, such as when a support structureimpinges on a highly angled portion of the object. In contrast, bypositioning support tips using the normals of the object surface, thesurface area of contact between a support tip and the object can bemaintained at, or close to, the minimum value, regardless of the objectgeometry.

As shown in the example of FIG. 1, support tips 18 and scaffolding 12have different orientations. However, the scaffolding may, in othercases, have the same orientation as the support tips if the geometry ofthe object being fabricated warrants such a configuration (e.g., theobject has a lower surface region parallel to build platform 10). Inaddition, the scaffolding may in general have any suitable geometry andis not limited to the “finger” shaped structure depicted in the exampleof FIG. 1.

Support tips 18 may have any suitable length, which may be an absolutelength, such as between less than 5 mm, such as 1 mm or 0.5 mm.Alternatively, or additionally, a support tip may have a length definedin proportion to an element of a scaffolding to which the support tip iscoupled; for example, less than 10% of a length of a scaffoldingelement.

It will be appreciated that, while the term “normal” is used herein todescribe the orientation of certain support tips, this may, in some usecases, refer to support tips oriented in a direction that is not, in amathematical sense, precisely 90° from a direction tangential to thesurface of an object. One of ordinary skill in the art will appreciatethat computational methods and techniques, including those describedherein, may produce orientations close to, but not exactly equal to,90°, and that it is within the scope of the term “normal” as used hereinthat an orientation may not be equal to precisely 90° from a directiontangential to a surface. As non-limiting examples, support tips maygenerated so as to be oriented between 80° and 100° from a directiontangential to the surface of an object; may be generated so as to beoriented between 85° and 95° from a direction tangential to the surfaceof an object; and/or may be generated so as to be oriented between 87.5°and 92.5° from a direction tangential to the surface of an object.

Similarly, the orientation of one or more support tips may be determinedbased on a normal direction that is not, in a mathematical sense,precisely 90° from a direction tangential to the surface of an object.Computational techniques may provide an estimate of a normal direction,but due to limitations inherent in performing calculations based on afinite number of data points (e.g., data points representing an object),a best estimate available may, in some cases, not be equal to amathematically precise normal direction that could have beenanalytically calculated on a purely mathematical object. It will beappreciated that various computational techniques may be used todetermine a normal direction, and any such techniques that provide anestimate of such a direction are within the scope of determining adirection “normal” to a surface as described herein. For example, somecomputational techniques to estimate a normal direction may generallyprovide orientations that are within an error range (e.g., 10%) of themathematically precise direction that is 90° from a tangent to asurface, but due to limited information may in some cases produceorientations that are as much as 45° from the precise normal direction.It is within the scope and spirit of the present invention thatmathematical techniques used to determine a normal direction may, insome cases, produce orientations that are as much as 45° or more fromthe precise normal direction for points on the surface of an object, yetin general for the same object will produce orientations that are muchcloser to the precise normal direction (e.g., within 10%).

As one non-limiting example of determining a direction normal to asurface of an object, the normal for a given location on the object maybe calculated by use of the following voxel approximation technique. Avoxel representation is constructed for the object which comprisesfilled voxels that represent the surface and/or the interior of theobject, and comprises empty voxels that represent the exterior of theobject. In such a representation, a voxel with an exposed face is avoxel wherein at least one side faces an empty voxel. A cubic voxel hassix faces that may be exposed, and so such a voxel may have exposedfaces in some combination of the +X, −X, +Y, −Y, +Z, and −Z directions.A voxel may also be surrounded by other filled voxels and thus may haveno exposed faces. To estimate a normal for a given location on theobject using such a representation, a voxel containing the location isfirst identified. Using the identified voxel, surrounding voxels in acube centered on the identified voxel are sampled to identify voxelswith exposed faces (e.g., sampling voxels in such a cube having 7 voxelsalong each side). For each sampled voxel with an exposed face, unitvectors are generated based on the exposed faces. For example, a voxelwith exposed +X and −Y faces would be decomposed into two unit vectors,one in the +X direction and one in the −Y direction. After decomposingeach exposed voxel in the cube, the normal for the given location isapproximated by performing vector addition of all unit vectors from alldecomposed exposed faces, centering the origin of the resulting normalvector at the center of the identified voxel.

The above non-limiting description is provided merely to illustrate onepossible exemplary technique for determining a direction normal to asurface of an object, and it will be appreciated that any othertechnique, including variations of the above-described technique, may beapplied to processes of generating and evaluating support structuresdescribed herein.

FIG. 2 depicts an object and a support structure that includes supporttips internal to the object, according to some embodiments. As shown inthe example of FIG. 2, support tips may also be employed in situationsin which the base of support scaffolding 30 attaches to an object 14 atits base, rather than to the build platform 10 as in the example ofFIG. 1. In such cases, the support scaffolding 30 may also be connectedat the base to the build platform, underlying build platform “raft”structures, or areas of object 14 using support tips 32 that intersectwith the relevant surfaces of the object at an angle normal to saidsurfaces.

FIG. 3 depicts an object and a support structure that includes supporttips whose geometry is varied based on self-supportedness of the object,according to some embodiments. As described above, it may beadvantageous to vary the geometry of an individual support tip, and thusits strength in various directions, based on the degree to which theconnection portion of an object is already supported.

As shown in the example of FIG. 3, steep portions 42 of object 14 may befabricated successfully using relatively little additional support, asthe underlying object may provide most, if not all, of the supportunderneath each layer to be deposited. Accordingly, support tips ofminimal strength 36 may be used for these regions. Alternatively,however, flatter downwards facing regions 40, may demand extensiveadditional support to avoid distortion, higher forces, and reducecosmetic defects. Accordingly, the support tips 34 for these sections 40may have a comparatively greater strength. The strength of a support tipmay be adjusted in any suitable way, including, but not limited to,adjusting the diameter of the support tip, adjusting the length of thesupport tip, adjusting the cross-sectional shape of the support tip(e.g., using geometries such as “X” shapes, hollow cylinders, triangles,rhombuses, rectangles, etc.), or combinations thereof.

The relationship between the degree of support provided by the objectbeing fabricated and the optimal size of support tips may exist along acontinuum, such that areas of intermediate supportedness receiveintermediate strength support tips 38.

FIG. 4 depicts an object and a support structure that includes supporttips whose geometry is varied based on distance from an axis applyingforces during a fabrication process, according to some embodiments. Asdiscussed above, it may be advantageous to modify one or more supporttips to improve the support provided to an object with regards to forcesexerted during the building process. One such example is illustrated inFIG. 4, which includes a stereolithographic printer 400 that utilizes a“peel” step which separates cured resin from the bottom of a transparenttray of resin 24. During operation, the resin tray 24 may be pivoted onits axis 28 causing downward motion 26, causing a greater force to beexerted on areas of the object further from the axis due to surfacetension of liquid held in the tray.

As shown in the example of FIG. 4, those support tips 22 located furtheraway from the axis of the tank 28 may be provided with greater strengththan those located closer to the axis 20. The strength of a support tipmay be adjusted in any suitable way, including, but not limited to,adjusting the diameter of the support tip, adjusting the length of thesupport tip, adjusting the cross-sectional shape of the support tip(e.g., using geometries such as “X” shapes, hollow cylinders, triangles,rhombuses, rectangles, etc.), or combinations thereof.

As shown in FIG. 4, support tips including tips 20 and 22 are orientednormal to the surface of object 14 at the location where the supporttips are coupled to the object. However, support tips may alternativelybe oriented at an angle offset from the normal in order to furtheroptimize the characteristics of the support structure by modifying thebreaking strength of support tips when exposed to forces from differingdirections.

FIG. 5A illustrates a first flow chart of a process for generatingsupport structure for an object, according to some embodiments. Method500 begins with step 502, in which one or more regions to which supportis to be provided are identified. The identification may be performed byanalyzing one or more regions of the object, and/or may be identified byreceived data (e.g., from another device). In use cases in which theregions are identified by analyzing an object, any suitable technique ortechniques for making such a determination may be used. In addition, anobject being analyzed and/or data identifying one or more regions may beaccessed in any suitable manner, including by accessing one or morecomputer readable media (including volatile and/or non-volatile media),receiving object data via a wired or wireless communication link, orcombinations thereof.

In step 504, one or more support points within a region of the objectare identified. The identification may be performed by analyzing one ormore regions of the object, and/or may be identified by received data(e.g., from another device). In some embodiments, preference is givenfor locating support points along edges or other surface discontinuitiesof an object in order to reduce visible artifacts.

In some embodiments, the one or more support points include one or morepoints located interior to the surface of an object. A support tipgenerated using one of these support points may therefore protrude somedistance into the object, for example between 0.1 mm and 1.0 mm, such as0.2 mm, into the object. Such a support tip may have increasedmechanical strength compared with a support tip that ends at the surfaceof the object, while not increasing the likelihood of defects present onthe object after removal of the support structure. Support tips thatprotrude into an object may have an orientation determined based on adirection normal to the surface of the object at a point in closeproximity to the support point, such as the point on the surface closestto the support point.

Irrespective of how the support points are identified, in step 506 asupport structure that includes support tips is generated. As describedabove, support tips may be coupled to a previously-identified supportpoint. The orientations of support tips included in the generatedsupport structure are oriented, at least in part, based on directionsnormal to the surface of the object at the support points. In use caseswhere one or more support points are located within the surface of theobject, the normal direction used to determine the orientation of asupport tip coupled to the interior support points may be a directionnormal to a point on the surface in close proximity to the supportpoint, such as the point on the surface closest to the support point.

In some embodiments, an orientation of at least one support tip includedin the support structure is calculated by determining an offset from thedirection normal to the surface at the corresponding support point. Forexample, a support tip may be oriented at an angle offset from thenormal, which may increase the breaking strength of the support tip whenexposed to a force in a particular direction.

FIG. 5B illustrates a second flow chart of a process for generatingsupport structure for an object, according to some embodiments. Method550 begins with step 554, in which an object is analyzed to determinewhich portions of the object may need support in order for those regionsto be fabricated successfully. Any suitable technique or techniques formaking such a determination may be used, including but not limited tocalculations for determining supportedness as described herein. Anobject being analyzed using in step 554 may be accessed in any suitablemanner, including by accessing one or more computer readable media(including volatile and/or non-volatile media), receiving object datavia a wired or wireless communication link, or combinations thereof.

At Step 556, one or more candidate positions for support to attach tothe object are identified using the information gathered during Step554. Identification of support attachment locations may be performed inany suitable way, including by analyzing the slope of downward-facing(e.g., facing toward a build platform) surfaces, detecting local lowpoints, and/or by performing a Boolean comparison of sequential layersto detect unsupported areas.

For each point identified on the object for support, the direction ofthe normal at that point is calculated based on the geometry of theobject during Step 560. In some use cases, geometry describing an objectmay be stored in an electronic format wherein normals for each trianglein a mesh of triangles are stored along with the coordinates of thetriangle in 3D space. Accordingly, in some embodiments, one or morenormals are calculated at a respective point by determining the ID ofthe triangle at that point in order to look up the normal associatedwith that triangle. Each normal may then be stored as a vector value fora given support point.

In Step 562, a second set of points are generated which are each apredefined distance from the object's surface, calculated using normalvectors identified in Step 560. In some embodiments, a point iscalculated by determining an offset from a support point in thedirection of the normal vector. The offset distance is preferably suchthat a sufficiently long support tip is generated to allow for thesupport to be easily broken away from the object, but not so much as tocause unwanted breaks to occur during the fabrication procedure. Such adistance may depend, at least in part, on the structural properties ofthe material used to fabricate the support. In some embodiments, theoffset distance is 1.0 mm or less. In some embodiments the offsetdistance may depend on additional factors, such as the cross area of thesupport tip, the angle between the support tip and the supportscaffolding, the geometry of the desired object, and/or other buildparameters such as layer height, peel settings, or resin type.

After the completion of the extensions along normals, two sets of pointshave been defined: a first set of points located on the surface of theobject representing the location where the support tip will be createdto intersect with the object; and a second set of points, located thepredefined distance from the object, representing the location where thesupport tip will join with support scaffolding extending up from thebuild platform or, in the case of internal supports, from a support tipattaching the support scaffolding to the object.

Following the generation of support tip length and direction, theappropriate geometry of each support tip is determined in Step 566. Insome embodiments, support tip strength is controlled by altering thedimensions, and thus the cross sectional surface area, of a rectangularprism. In some embodiments, support tips include rectangular prismshaving dimensions of 0.5 mm by 0.5 mm.

In some embodiments, the dimensions of the support tip may be furthermodified with reference to multiple weighted factors including thedistance from the axis and the supportedness, the results of mechanicalanalysis of the material, and/or an extent to which the object demandssupport at each contact point as indicated. When using a strengthdetermination, support tips are added to the model of the object in Step568 such that each has a surface area and dimensions that depend on thestrength determined in the preceding step.

In Step 568, the support tips are generated based at least in part onthe set of points on the surface of the object identified in Step 556,and on the set of support tip base points identified in Step 562.

In Steps 570-574, the underlying support scaffolding that connects tothe base of each support tip is generated. In some embodiments, thesecond set of points generated above in Step 562 are projected onto a2-dimensional plane representing the build platform (Step 570). Usingeach point as a node, a set of paths between connected nodes may begenerated in Step 572 by calculating a minimum spanning forest or othergraph structure connecting all nodes. For example, algorithms such asbut not limited to Prim's, Kruskal's or Boruvka's algorithm may be usedto calculate the edges of such a spanning forest.

In Step 574, the edges identified in Step 572 are extruded up from thebuild platform, forming thin walls of a predefined thickness. Thesewalls provide the support scaffolding connecting to the base of eachsupport tip. Each portion of the wall is extruded upwards until itcontacts the base of the support tip or, alternatively, it comes withina preset distance of an object. The generation of support scaffoldingusing minimum spanning trees presents several advantages over thetechniques known previously in the art. In the first instance, minimumspanning trees use comparatively less material than structures known inthe art, such as linear grids or vertical pins, while providing enhancedstability through the intersection of multiple walls at nodes withseveral edges. Such intersections, moreover, provide increased stabilityover prior art structures such as vertical pins while using lessmaterial and being more easily removed than other prior art structuressuch as linear grids.

Finally, both the walls forming the support scaffolding and support tipsare combined into the model for printing in Step 576.

FIG. 6A-B illustrate isometric and top-down 3-D representations of asupport structure for a spherical object, according to some embodiments.As depicted in the example shown in FIGS. 6A and 6B, the resultingstructure generated in order to support object 56, which is a sphere,consists of support tips 58 oriented with the normals of theintersecting surface, which are in turn supported by scaffolding 60arranged in a graph structure connecting each support point andattaching the support point to a base 62. Such graph structures mayinclude structures such as minimal spanning trees or other graphs. Inaddition, graph structures may be optimized for additional parametersother than material usage, including desired weakness in particulardirections, increased strength in particular directions, and/or toaccommodate particular regions of object geometry, such as flatdownwards or upwards facing surfaces.

As discussed above, support tips may be created as rectangular prisms.However, other shapes, including cylinders or triangular prisms, mayalternatively or additionally be used for support tips within a supportstructure. In some embodiments, dimensions of the support tips can varyalong different axes. Such asymmetric support tips may be used, forexample, to resist forces during the fabrication processes expectedalong certain vectors while permitting removal by the user with reducedforce.

FIG. 7A illustrates a top-down schematic view of a first arrangement ofsupport tips arranged radially with long axis directed out from thecentroid of an object, according to some embodiments. As can be seen inFIG. 7A, support tips 44, not drawn to scale, may interface with anobject with a greater length than width. As further shown, such supporttips 44 can be advantageously oriented so as to ensure that the longaxis of each support tip runs tangent to lines extending out from thecentroid of the object. Alternatively, or additionally, support tips maybe arranged so as to place the long axis of each support tip tangent tolines extending out from the centroid of the support location or tangentto lines extending out from a predefined point in space.

FIG. 7B illustrates a top-down schematic view of a second arrangement ofsupport tips arranged radially with long axis directed out from thecentroid of an object, according to some embodiments. As shown in FIG.7B, support tips 48 may be rectangular in cross-section. One havingskill in the art will appreciate that a wide range of shapes may be usedsuch that high aspect ratio shapes are oriented with the long axis ofthe shape pointing away from a centroid of an object. Advantageously,such support tips may resist the typically linear forces of the additivemanufacturing process, but may be removed from the desired object by theapplication of a comparatively lower rotational force 46.

FIG. 7C illustrates a top-down schematic view of support tips arrangedlinearly with a long axis directed orthogonally from an expecteddirection of a force exerted during a fabrication process, according tosome embodiments. In the example of FIG. 7C, the geometry of individualsupport tips are arranged so as to position the long axis of eachsupport tip at a 90 degree angle to the direction of a force expectedduring the build process such as, for example, rotation or tilting aboutan axis 54. As above, such a configuration may provide substantialresistance to forces exerted during the building process while allowingfor easier removal by the application of force 52 at an orthogonal angleto such build forces.

As discussed above, because support structures, even those includingsupport tips, can have negative impacts on the desired final object, itmay be beneficial to allow a user to review where and how supportstructures will be created and, in certain circumstances, to edit oralter manually or automatically generated support structures so as todirect the placement of the support. However, there has previously beenno way for a user to properly evaluate the consequences of placingsupport structure without experimentation and attempts to print thedesired final object using different potential support structures. Suchexperimentation is costly and wasteful and often does not result inoptimal, or even acceptable, placement of support structures.

Accordingly, following below are more detailed descriptions of variousconcepts related to, and embodiments of, providing an indication ofsupportedness of an object to a user. By utilizing these indications,the user can ensure that advantageous placement of support structurescan be achieved.

It should be appreciated that various aspects described herein may beimplemented in any of numerous ways. Examples of specificimplementations are provided herein for illustrative purposes only. Inaddition, the various aspects described in the embodiments below may beused alone or in any combination, and are not limited to thecombinations explicitly described herein. For example, the exemplaryinterfaces shown in FIGS. 9A-C utilize color to provide a visualindication of supportedness of regions of the objects. However, ingeneral any suitable visual indication of supportedness may be providedvia a user interface to indicate the supportedness of a region of anobject. For example, any shading (including blending of colors) and/orpatterning (e.g., striping, cross-hatching, etc.) of one or more GUIelements (e.g., an object being depicted and/or a support structurebeing depicted) may be used to denote supportedness, with or without theuse of multiple colors to distinguish between different supportednessvalues. Alternatively, or additionally, text, one or more symbols (e.g.,arrows, icons, etc.), user controls (e.g., sliders, radio buttons, menuoptions, etc.), or combinations thereof, with or without the use ofcolors, may be used to denote supportedness either alone or incombination.

FIG. 8 illustrates an exemplary object and an exemplary supportstructure, according to some embodiments. FIG. 8 illustrates graphicaluser interface 800, which displays a three-dimensional view of an object810 to be fabricated via one or more additive fabrication techniques.Graphical user interface 800 further displays a three-dimensional viewof support structure 820 which is also to be fabricated via one or moreadditive fabrication techniques, and which is configured providemechanical support to object 810 during fabrication of the object andthe support structure.

As shown in the example of FIG. 8, supports 820 for an object 810desired to be printed are generated between a build platform 805 andcertain locations touching the object. These supports may be determinedin any suitable manner, including but not limited to, being manuallyplaced using software tools (e.g., computer aided design (CAD) tools)and/or may be automatically generated using any suitable algorithms.

As shown in the example of FIG. 8, support structures need not touchupon the desired object at all points. Although methodologies may existin the art for determining where support may be provided in order toensure successful fabrication of an object, it is generally understoodthat most materials capable of being used in layer-by-layer additivemanufacturing techniques possess sufficient mechanical and structuralproperties that certain portions can be considered self-supporting,despite the fact that there is no layer immediately below said portion.The self-supportedness of a given portion of an object, however, cansometimes be a difference in degree rather than of kind, particularly ininstances wherein the user is prepared to accept certain amounts ofdeformation or other surface imperfections in the final object.

FIGS. 9A-C illustrate three views of the exemplary object and exemplarysupport structure shown in FIG. 8, but additionally include anindication of the supportedness of the object, according to someembodiments. FIGS. 9A-C illustrate graphical user interface 900, whichdisplays a three-dimensional view of object 810. Each of FIGS. 9A-Crepresents a different view of the object 810 shown in the graphicaluser interface, for example, by using tools to rotate the viewing anglewithin the interface.

Graphical user interface 900 provides indications for regions 911 and912 which indicate whether the relevant region of the desired object mayhave adequate or inadequate support for printing using a specifiedadditive fabrication technique, fabrication material, support structuregeometry, and/or build conditions. For any given combination of additivefabrication technique, fabrication material, support structure geometry,and build conditions, the ability of a given layer to be self-supportingmay be assessed or determined. As described below, each portion of theobject for fabrication is evaluated to determine the extent of its“supportedness,” used herein as a term to indicate the varying degreethat a portion of the object is mechanically and structurally supportedor tied to other portions of the object. It is not necessary thatsupportedness be exact for the advantages of the present invention toapply. Rather, it is envisioned that supportedness may be an inexactapproximation of the mechanical and structural characteristics of anobject calculated through various heuristics with predictive value.Using calculated supportedness values, each portion of the desiredobject can be colored to indicate to the user whether there is adequatesupport.

Region 911 is displayed using a different color than region 912, whichindicates whether the supportedness value of each region is above orbelow a threshold deemed to be adequate support for a given materialunder certain build conditions. In the example of FIGS. 9A-C, region 911has a supportedness value below this threshold, whereas region 912 has asupportedness value above this threshold. In some embodiments, more thantwo colors are used to indicate the supportedness of regions of anobject.

In some embodiments, green coloration indicates a supportedness valueabove a certain threshold, deemed to be adequate support for a givenmaterial under certain build conditions; and red coloration indicates asupportedness value below a certain threshold, which may or may not bethe same as the previous threshold, deemed to be inadequate support fora given material under certain build conditions. However, it will beappreciated that these colors are provided merely as an example, as thepresent invention is not limited to any particular mode of display, andany type of user interfaces may be used to depict similar information.

In some embodiments, a blend of colorations may be used to indicatecertain regions with borderline or ambiguous supportedness values.Alternatively, or additionally, a blend of colorations may be used toindicate regions in which the supportedness is transitioning between twovalues (e.g., between a region of high supportedness and a region of lowsupportedness). In some embodiments, patterns such as cross-hatching maybe used to indicate supportedness of one or more regions.

In some embodiments, based on the properties of the build material, andother parameters of the building process, one or more thresholds used tomay be set to differing values. Advantageously, once determined throughexperimentation on certain test objects, the threshold of a given set oftechnique, material, and parameters can be reused when indicating thesupportiveness of future objects.

Using the indications depicted in FIGS. 9A-C, the user can take avariety of steps to improve the quality, speed, and cost of the processmanufacturing the desired object, such as those depicted in method 1000shown in FIG. 10A and/or method 1050 shown in FIG. 10B. As one example,a user may choose to edit a support structure in order to add additionalsupports where a lack of supportedness is indicated. Alternatively, theuser may remove support structure where the object has more thansufficient levels of support. As yet another example, the user, and/oran appropriate algorithm, can reorient the object so as to modify thegeometry to which a support structure is to be coupled, and thus improvethe quality, speed, and cost of the final object. In each of theforegoing examples of user interaction, the techniques described hereincan be used to evaluate the relative success or merits of each supportstructure configuration without needing to run experiments using theactual additive manufacturing process.

FIG. 10A illustrates a flow chart of an exemplary process for evaluatinga support structure associated with an object, according to someembodiments. Method 1000 begins with step 1001, in which arepresentation of a support structure that provides mechanical supportto an object is obtained. The support structure may be obtained, forexample, by generating the support structure (e.g., generating thesupport structure based on the object), and/or by retrieving data thatdescribes the support structure.

In step 1002, the supportedness of a first region of the object iscalculated. Calculation of supportedness of the object may comprise thedetermination of any number of supportedness values associated with anynumber of locations within the first region.

In general, any suitable technique or techniques may be used to evaluatethe structural and mechanical properties of an object, any of which maybe used to assign a supportedness value to any number of regions of anobject. In some embodiments, one or more supportedness values arecalculated by the following technique: First, the object is divided intorectangular units of pre-defined and uniform dimensions, such as“voxels.” Supportedness values are calculated for each unit of theobject, thus providing information that can be used to indicatesupportiveness as indicated above. Those units that touch upon units ofsupport structure, or on the build platform, are deemed to have a firstsupportedness value that indicates completely supported material.Supportedness values of each unit are calculated based on thesupportedness of neighboring units in the layer below. Areas outside ofthe object, and/or voids within the object, are represented by unitswith a defined supportedness of zero, indicating that they provide nosupport to neighboring units. Depending on the material or, as describedbelow, the degree of desired accuracy, various functions can be used toderive the supportedness of a unit based on underlying units.

In some embodiments, an analysis is conducted wherein the variousphysical limitations of the material to self-support, includingcompressive strength, tensile strength, shear strength, and flexibilityare represented and approximated by the application of a single factor,referred to here as epsilon, governing the transmission of“supportedness” through successive voxels. For example, thesupportedness of a voxel may be represented as a weighted average, sum,or minima of supportedness contributed by neighboring voxels, weightedby epsilon. Such an approach may reduce the extent to which physicalmodelling is performed while providing substantial predictive value. Insome embodiments, the values of epsilon may depend, at least in part, onthe fabrication material used to fabricate an object and/or a supportstructure. In some embodiments, epsilon is equal to between 0.1 and 0.3,for example 0.2. In general, epsilon values for a given set of buildparameters may be determined by experimentation using a suitable testobject.

As will be appreciated, various other techniques of calculating thesupportedness of a given region of an object may be chosen, depending onthe extent of a desire for accuracy, the tolerance for extensivecomputation, and/or the nature of the material. Depending on a desireddegree of accuracy, various techniques such as, but not limited to,finite element analysis or physical models such as Euler-Bernoulli beamcalculations, may be used to calculate the degree to regions of theobject are supported. Alternatively, or additionally, techniques such asthose to calculate the position of support structures, for example, maybe modified in order to provide information on supportedness. Thetechniques disclosed herein, however, are equally applicable to anymethod of calculating supportedness, so long as said method providessome predictive information regarding how the material would behave whenused in an additive fabrication process.

Techniques described herein are applicable to situations wherein, inaddition to gravity, support structures are provided to counteract otherforces, such as a warping or distorting force caused by curing,deposition, and/or other steps during an additive fabrication process.In addition, a calculation of supportedness may advantageouslyincorporate parameters regarding the expected process used to finish theobject, including whether said finishing process places particularstress on certain regions of the desired object. In such instances,support structures may support the object against forces pulling inmultiple vectors. In such instances, supportedness values may becombined in various ways. Depending on the nature of the forces appliedagainst the model during the additive fabrication process, supportednessvalues can be chosen based on the maximum, minimum, average, or vectorproduct of competing forces. Alternatively, or additionally, such forcesmay be included within the finite element analysis described above.Alternatively, or additionally, supportedness due to different types offorces may be kept distinct for each region of the model such that theend user can choose to visualize some or all of the independent sets ofsupportedness values.

In step 1003, the support structure for which a representation wasobtained in step 1001 and/or the object is/are depicted via a graphicaluser interface (GUI). For example, a 3-dimensional representation of thesupport structure and/or object may be depicted in a GUI. In step 1004,the supportedness of the first region is indicated by coloring a portionof the GUI. While step 1003 and 1004 are described as separate steps inthe example of FIG. 10A, it will be appreciated that the actions thusdescribed may be performed simultaneously. For example, the supportstructure and/or object may be depicted via the GUI at the same timethat the supportedness of the first region is indicated.

Coloring the GUI may comprise determining and thus depicting the color,pattern and/or shade of any number of elements of the GUI. It will beappreciated that a single color may be depicted in numerous ways thatutilize multiple colors, including but not limited to by dithering,cross-hatching, anti-aliasing, etc. In some use cases, one or more GUIelements may be colored using a plurality of colors (e.g., by shading,dithering, anti-aliasing, etc.). In some embodiments, the color of thefirst region of the object is determined based on a supportedness of thefirst region, and indicated via the GUI. For example, when the firstregion has a supportedness above a threshold, the region of the objectmay have a first color (which, as described above, may in practiceinclude a mix of colors due to shading or other effects) chosen todenote a level of supportedness above the threshold.

Techniques described herein may be directed to support structuresthemselves, in addition to, or in alternative to, the supportedness of agiven object. While support structure on a given layer may providesupport for layers above said given layer, said given layer may itselfbenefit from support structures below said given layer. In such cases,one or more portions of the support structure may be treated as anobject for the purposes of calculating supportedness values.

Although the foregoing examples include embodiments whereinsupportedness values are calculated prior to display, other embodimentsare possible and within the scope of disclosed aspects of the presentinvention. As one example, display of indications of supportedness maybe performed in parallel with calculations of supportedness such thatindications are updated (e.g., on a display) as calculations proceed. Inaddition, the calculation and indication of supportedness may be limitedto a determination at a particular depth of an object, or within a shellsurrounding the exterior of the object.

Techniques for determining the supportedness of one or more regions ofan object may be based on any suitable representation of the object. Forexample, as described above, objects may be defined by electronic data,such as an STL file. Regardless of the way in which an object isdefined, a representation of the object may be obtained in any suitableway in performing the methods and techniques described herein, includingby reading data from one or more computer storage media, or bygenerating the representation of the object (e.g., using a proceduralgeneration technique). In some embodiments, supportedness of an objectis determined, at least in part, by accessing a representation of theobject stored on one or more computer readable media, which may belocated in any suitable location or locations.

Furthermore, techniques for determining the supportedness of one or moreregions of an object may be based on any suitable representation of asupport structure. For example, a support structure may be defined byelectronic data, such as an STL file, and/or may be generated bysuitable software (e.g., generated based on an associated object).Furthermore, the representation of the support structure may be obtainedin any suitable way, including by generating the support structure(e.g., from an object) and/or by reading the representation from astorage device. In some embodiments, the extent to which a supportstructure supports an object is determined, at least in part, byaccessing a representation of the support structure stored on one ormore computer readable media, which may be located in any suitablelocation or locations.

A determination of supportedness may be made based on the representationof the support structure in addition to any suitable informationregarding an associated object. For example, the determination may bemade based on representations of both the support structure and theobject, but may also be based on a representation of the supportstructure in addition to information regarding the object. For example,only part of an object may be evaluated for supportedness, andaccordingly a complete representation of the object may not be necessaryin making said evaluation.

FIG. 11 illustrates an example of a suitable computing systemenvironment 1100 on which aspects of the invention may be implemented.For example, the computing system environment 1100 may be used todetermine the supportedness of one or more regions of an object, togenerate a support structure for an object, to generate support tips fora support structure, to indicate the supportedness of one or moreregions of an object via a graphical user interface, to interface withone or more devices to effect additive fabrication of an object and/or asupport structure, or any combinations thereof. Such a computingenvironment may represent a home computer, a tablet, a mobile device, aserver and/or any another computing device.

The computing system environment 1100 is only one example of a suitablecomputing environment and is not intended to suggest any limitation asto the scope of use or functionality of the invention. Neither shouldthe computing environment 1100 be interpreted as having any dependencyor requirement relating to any one or combination of componentsillustrated in the exemplary operating environment 1100.

Aspects of the invention are operational with numerous other generalpurpose or special purpose computing system environments orconfigurations. Examples of well-known computing systems, environments,and/or configurations that may be suitable for use with the inventioninclude, but are not limited to, personal computers, server computers,hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputers, mainframe computers,distributed computing environments that include any of the above systemsor devices, and the like.

The computing environment may execute computer-executable instructions,such as program modules. Generally, program modules include routines,programs, objects, components, data structures, etc. that performparticular tasks or implement particular abstract data types. Theinvention may also be practiced in distributed computing environmentswhere tasks are performed by remote processing devices that are linkedthrough a communications network. In a distributed computingenvironment, program modules may be located in both local and remotecomputer storage media including memory storage devices.

With reference to FIG. 11, an exemplary system for implementing aspectsof the invention includes a general purpose computing device in the formof a computer 1110. Components of computer 1110 may include, but are notlimited to, a processing unit 1120, a system memory 1130, and a systembus 1121 that couples various system components including the systemmemory to the processing unit 1120. The system bus 1121 may be any ofseveral types of bus structures including a memory bus or memorycontroller, a peripheral bus, and a local bus using any of a variety ofbus architectures. By way of example, and not limitation, sucharchitectures include Industry Standard Architecture (ISA) bus, MicroChannel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus also known as Mezzanine bus.

Computer 1110 typically includes a variety of computer readable media.Computer readable media can be any available media that can be accessedby computer 1110 and includes both volatile and nonvolatile media,removable and non-removable media. By way of example, and notlimitation, computer readable media may comprise computer storage mediaand communication media. Computer storage media includes both volatileand nonvolatile, removable and non-removable media implemented in anymethod or technology for storage of information such as computerreadable instructions, data structures, program modules or other data.Computer storage media includes, but is not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can accessed by computer 1110. Communication media typicallyembodies computer readable instructions, data structures, programmodules or other data in a modulated data signal such as a carrier waveor other transport mechanism and includes any information deliverymedia. The term “modulated data signal” means a signal that has one ormore of its characteristics set or changed in such a manner as to encodeinformation in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared and other wireless media. Combinations of the any of the aboveshould also be included within the scope of computer readable media.

The system memory 1130 includes computer storage media in the form ofvolatile and/or nonvolatile memory such as read only memory (ROM) 1131and random access memory (RAM) 1132. A basic input/output system 1133(BIOS), containing the basic routines that help to transfer informationbetween elements within computer 1110, such as during start-up, istypically stored in ROM 1131. RAM 1132 typically contains data and/orprogram modules that are immediately accessible to and/or presentlybeing operated on by processing unit 1120. By way of example, and notlimitation, FIG. 11 illustrates operating system 1134, applicationprograms 1135, other program modules 1136, and program data 1137.

The computer 1110 may also include other removable/non-removable,volatile/nonvolatile computer storage media. By way of example only,FIG. 11 illustrates a hard disk drive 1141 that reads from or writes tonon-removable, nonvolatile magnetic media, a magnetic disk drive 1151that reads from or writes to a removable, nonvolatile magnetic disk1152, and an optical disk drive 1155 that reads from or writes to aremovable, nonvolatile optical disk 1156 such as a CD ROM or otheroptical media. Other removable/non-removable, volatile/nonvolatilecomputer storage media that can be used in the exemplary operatingenvironment include, but are not limited to, magnetic tape cassettes,flash memory cards, digital versatile disks, digital video tape, solidstate RAM, solid state ROM, and the like. The hard disk drive 1141 istypically connected to the system bus 1121 through an non-removablememory interface such as interface 1140, and magnetic disk drive 1151and optical disk drive 1155 are typically connected to the system bus1121 by a removable memory interface, such as interface 1150.

The drives and their associated computer storage media discussed aboveand illustrated in FIG. 11, provide storage of computer readableinstructions, data structures, program modules and other data for thecomputer 1110. In FIG. 11, for example, hard disk drive 1141 isillustrated as storing operating system 1144, application programs 1145,other program modules 1146, and program data 1147. Note that thesecomponents can either be the same as or different from operating system1134, application programs 1135, other program modules 1136, and programdata 1137. Operating system 1144, application programs 1145, otherprogram modules 1146, and program data 1147 are given different numbershere to illustrate that, at a minimum, they are different copies. A usermay enter commands and information into the computer 1110 through inputdevices such as a keyboard 1162 and pointing device 1161, commonlyreferred to as a mouse, trackball or touch pad. Other input devices (notshown) may include a microphone, joystick, game pad, satellite dish,scanner, or the like. These and other input devices are often connectedto the processing unit 1120 through a user input interface 1160 that iscoupled to the system bus, but may be connected by other interface andbus structures, such as a parallel port, game port or a universal serialbus (USB). A monitor 1191 or other type of display device is alsoconnected to the system bus 1121 via an interface, such as a videointerface 1190. In addition to the monitor, computers may also includeother peripheral output devices such as speakers 1197 and printer 1196,which may be connected through a output peripheral interface 1195.

The computer 1110 may operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computer1180. The remote computer 1180 may be a personal computer, a server, arouter, a network PC, a peer device or other common network node, andtypically includes many or all of the elements described above relativeto the computer 1110, although only a memory storage device 1181 hasbeen illustrated in FIG. 11. The logical connections depicted in FIG. 11include a local area network (LAN) 1171 and a wide area network (WAN)1173, but may also include other networks. Such networking environmentsare commonplace in offices, enterprise-wide computer networks, intranetsand the Internet.

When used in a LAN networking environment, the computer 1110 isconnected to the LAN 1171 through a network interface or adapter 1170.When used in a WAN networking environment, the computer 1110 typicallyincludes a modem 1172 or other means for establishing communicationsover the WAN 1173, such as the Internet. The modem 1172, which may beinternal or external, may be connected to the system bus 1121 via theuser input interface 1160, or other appropriate mechanism. In anetworked environment, program modules depicted relative to the computer1110, or portions thereof, may be stored in the remote memory storagedevice. By way of example, and not limitation, FIG. 11 illustratesremote application programs 1185 as residing on memory device 1181. Itwill be appreciated that the network connections shown are exemplary andother means of establishing a communications link between the computersmay be used.

The various methods or processes outlined herein may be implemented inany suitable hardware. Additionally, the various methods or processesoutlined herein may be implemented in a combination of hardware and ofsoftware executable on one or more processors that employ any one of avariety of operating systems or platforms. For example, the variousmethods or processes may utilize software to instruct a processor todetermine the supportedness of one or more regions of an object to befabricated via one or more additive fabrication techniques; and/or togenerate a support structure, with or without support tips, for anobject to be fabricated via one or more additive fabrication techniques.Example of such approaches are described above. However, any suitablecombination of hardware and software may be employed to realize any ofthe embodiments discussed herein.

In this respect, various inventive concepts may be embodied as at leastone non-transitory computer readable storage medium (e.g., a computermemory, one or more floppy discs, compact discs, optical discs, magnetictapes, flash memories, circuit configurations in Field Programmable GateArrays or other semiconductor devices, etc.) encoded with one or moreprograms that, when executed on one or more computers or otherprocessors, implement the various embodiments of the present invention.The non-transitory computer-readable medium or media may betransportable, such that the program or programs stored thereon may beloaded onto any computer resource to implement various aspects of thepresent invention as discussed above.

The terms “program” or “software” are used herein in a generic sense torefer to any type of computer code or set of computer-executableinstructions that can be employed to program a computer or otherprocessor to implement various aspects of embodiments as discussedabove. Additionally, it should be appreciated that according to oneaspect, one or more computer programs that when executed perform methodsof the present invention need not reside on a single computer orprocessor, but may be distributed in a modular fashion among differentcomputers or processors to implement various aspects of the presentinvention.

Computer-executable instructions may be in many forms, such as programmodules, executed by one or more computers or other devices. Generally,program modules include routines, programs, objects, components, datastructures, etc. that perform particular tasks or implement particularabstract data types. Typically, the functionality of the program modulesmay be combined or distributed as desired in various embodiments.

Having herein described several embodiments, several advantages ofembodiments of the present application should be apparent. One advantageis that embodiments may allow for an object fabricated via one or moreadditive fabrication techniques to be provided with mechanical supportin the desired way while also minimizing the support structure's effecton the quality of the fabricated object.

Various inventive concepts may be embodied as one or more methods, ofwhich examples have been provided. For example, methods of generating asupport structure for an object, and methods of evaluating a supportstructure have been provided herein. The acts performed as part of anymethod described herein may be ordered in any suitable way. Accordingly,embodiments may be constructed in which acts are performed in an orderdifferent than illustrated, which may include performing some actssimultaneously, even though these acts may have been shown as sequentialacts in illustrative embodiments.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein, unless clearlyindicated to the contrary, should be understood to mean “at least one.”

As used herein, the phrase “at least one,” in reference to a list of oneor more elements, should be understood to mean at least one elementselected from any one or more of the elements in the list of elements,but not necessarily including at least one of each and every elementspecifically listed within the list of elements and not excluding anycombinations of elements in the list of elements. This definition alsoallows that elements may optionally be present other than the elementsspecifically identified within the list of elements to which the phrase“at least one” refers, whether related or unrelated to those elementsspecifically identified.

The phrase “and/or,” as used herein, should be understood to mean“either or both” of the elements so conjoined, i.e., elements that areconjunctively present in some cases and disjunctively present in othercases. Multiple elements listed with “and/or” should be construed in thesame fashion, i.e., “one or more” of the elements so conjoined. Otherelements may optionally be present other than the elements specificallyidentified by the “and/or” clause, whether related or unrelated to thoseelements specifically identified. Thus, as a non-limiting example, areference to “A and/or B”, when used in conjunction with open-endedlanguage such as “comprising” can refer, in one embodiment, to A only(optionally including elements other than B); in another embodiment, toB only (optionally including elements other than A); in yet anotherembodiment, to both A and B (optionally including other elements); etc.

As used herein, “or” should be understood to have the same meaning as“and/or” as defined above. For example, when separating items in a list,“or” or “and/or” shall be interpreted as being inclusive, i.e., theinclusion of at least one, but also including more than one, of a numberor list of elements, and, optionally, additional unlisted items. Onlyterms clearly indicated to the contrary, such as “only one of” or“exactly one of,” will refer to the inclusion of exactly one element ofa number or list of elements. In general, the term “or” as used hereinshall only be interpreted as indicating exclusive alternatives (i.e.“one or the other but not both”) when preceded by terms of exclusivity,such as “either,” “one of,” “only one of,” or “exactly one of.”

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” “having,” “containing”, “involving”, andvariations thereof, is meant to encompass the items listed thereafterand additional items.

Having described several embodiments of the invention in detail, variousmodifications and improvements will readily occur to those skilled inthe art.

For example, techniques of evaluating a support structure weredescribed. These techniques may be applied in other contexts. Forexample, evaluation of any aspect of any structure used in additivefabrication may utilize techniques as described herein. Suchmodifications and improvements are intended to be within the spirit andscope of the invention. Accordingly, the foregoing description is by wayof example only, and is not intended as limiting.

What is claimed is:
 1. A method of generating a support structure for anobject, the support structure and the object to be fabricated via one ormore additive fabrication techniques, comprising: identifying one ormore regions of the object as one or more regions to which mechanicalsupport is to be provided; identifying one or more support points withinat least a first region of the one or more regions; and generating thesupport structure for the object, the support structure comprising oneor more support tips coupled to the object at the one or more supportpoints, the support tips being generated based at least in part on adirection normal to the surface of the object at the respective supportpoint.
 2. The method of claim 1, further comprising fabricating thesupport structure using the one or more additive fabrication techniques.3. The method of claim 1, wherein at least a subset of the one or moresupport tips are oriented in the direction normal to the surface of theobject at the respective support point.
 4. The method of claim 1,wherein orientations of each of the one or more support tips aredetermined by applying an offset, based on directions of expected forcesat the respective support point, to the direction normal to the surfaceof the object at the respective support point.
 5. The method of claim 1,wherein at least a first support tip of the one or more support tips hasa strength determined based at least in part on a degree to which thefirst region is self-supporting.
 6. The method of claim 1, wherein theone or more support tips have geometries that depend, at least in part,upon a degree of support to avoid mechanical damage calculated based ondirections of expected forces at respective support points.
 7. Themethod of claim 6, wherein the geometries include an asymmetriccross-sectional area of contact with the object.
 8. The method of claim7, wherein at least a subset of the support tip geometries include along axis and a short axis, and wherein the tips of the subset arepositioned on the object such that the long axis of each tip issubstantially perpendicular to a line extending from a centroid of theobject.
 9. The method of claim 7, wherein at least a subset of thesupport tip geometries include a long axis and a short axis, and whereinthe tips of the subset are positioned on the object such that the longaxis of each tip is substantially normal to a direction of a forcepredicted to be exerted on the object during fabrication thereof. 10.The method of claim 1, further comprising determining a plurality oflayers that together correspond to a shape of the support structure. 11.The method of claim 1, wherein the support structure comprises ascaffolding coupled to a first support tip of the one or more supporttips, and wherein at least a portion of the scaffolding has anorientation different from an orientation of the first support tip. 12.At least one non-transitory computer readable medium comprising anexecutable program that, when executed, causes a computer to perform amethod of generating a support structure for an object, the supportstructure and the object to be fabricated via one or more additivefabrication techniques, the method comprising: identifying one or moreregions of the object as one or more regions to which mechanical supportis to be provided; identifying one or more support points within atleast a first region of the one or more regions; and generating thesupport structure for the object, the support structure comprising oneor more support tips coupled to the object at the one or more supportpoints, the support tips being generated based at least in part on adirection normal to the surface of the object at the respective supportpoint.
 13. The at least one non-transitory computer readable medium ofclaim 12, wherein at least a subset of the one or more support tips areoriented in the direction normal to the surface of the object at therespective support point.
 14. The at least one non-transitory computerreadable medium of claim 12, wherein orientations of each of the one ormore support tips are determined by applying an offset, based ondirections of expected forces at the respective support point, to thedirection normal to the surface of the object at the respective supportpoint.
 15. The at least one non-transitory computer readable medium ofclaim 12, wherein at least a first support tip of the one or moresupport tips has a strength determined based at least in part on adegree to which the first region is self-supporting.
 16. The at leastone non-transitory computer readable medium of claim 12, wherein the oneor more support tips have geometries that depend, at least in part, upona degree of support to avoid mechanical damage calculated based ondirections of expected forces at respective support points.
 17. The atleast one non-transitory computer readable medium of claim 16, whereinthe geometries include an asymmetric cross-sectional area of contactwith the object.
 18. The at least one non-transitory computer readablemedium of claim 17, wherein at least a subset of the support tipgeometries include a long axis and a short axis, and wherein the tips ofthe subset are positioned on the object such that the long axis of eachtip is substantially perpendicular to a line extending from a centroidof the object.
 19. The at least one non-transitory computer readablemedium of claim 17, wherein at least a subset of the support tipgeometries include a long axis and a short axis, and wherein the tips ofthe subset are positioned on the object such that the long axis of eachtip is substantially normal to a direction of a force predicted to beexerted on the object during fabrication thereof.
 20. The at least onenon-transitory computer readable medium of claim 12, wherein the methodfurther comprises determining a plurality of layers that togethercorrespond to a shape of the support structure.
 21. The at least onenon-transitory computer readable medium of claim 12, wherein the supportstructure comprises a scaffolding coupled to a first support tip of theone or more support tips, and wherein at least a portion of thescaffolding has an orientation different from an orientation of thefirst support tip.